# CII-DT-097

Source: https://xmlvalid.com/rules/CII-DT-097

> Date time string with format attribute 102 shall be YYYYMMDD.

- Level: error
- Rule sets: EN 16931 rules (CII) 1.3.17, EN 16931 rules 1.3.16 (CII), EXTENDED-CTC-FR rules (CII) 1.4.0.04, Factur-X EXTENDED rules 1.09.2
- Context: `//udt:DateTimeString[@format = '102']`
- Test: `matches(.,'^\s*(\d{4})(1[0-2]|0[1-9]){1}(3[01]|[12][0-9]|0[1-9]){1}\s*$')`

Validate a document against these rules: https://xmlvalid.com/validate